As announced, the PDB separated theoretical model coordinate files from the main archive on July 1, 2002. Since that date, the main PDB archive has consisted of structures determined using experimental methods only.

All theoretical models (current and obsolete) are kept in a separate location on the PDB archive and are available for download only. Theoretical models are not included in statistics.

As of October 15, 2006, PDB depositions have been restricted to atomic coordinates that are substantially determined by experimental measurements on specimens containing biological macromolecules. Thus, theoretical model depositions (such as models determined purely in silico using, for example, homology or ab initio methods) will no longer be accepted. For more information, please see the wwPDB announcement.